Removal of phenols from their aqueous solutions with low-capacity ionexchange resins



April 20. 1965 Filed Sept. 20, 1960 c. w. RIEMAN Ill 3,179,703 REMOVALOF PHENOLS FROM THEIR AQUEOUS SOLUTIONS WITH LOW-CAPACITY ION-EXCHANGERESINS 2 Sheets-Sheet 1 M =Mo/0/'/'/y oi pheno/ in eguf/l'rl'um W/Y/Ires/n. MmO/S. or aheno/absorbed aerg. 0/ res/l7.

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Casper Will/0m R/em on 4 2 BY Z i W HTTORNEY United States Patent (33,179,703 REMOVAL OF PHENOLS FRQM THERE AQUE- OUS SQLUTETENS WITHLQW-CAPACETY ION- EXCHANGE RESINS Caspar William Riemann HT, NewBrunswick, N..l., as-

signor to The Dow Chemical Company, Midland, Mich, a corporation ofDelaware Filed Sept. 20, 1960, Ser. No. 57,255 4 Claims. (Cl. Zed-621)This invention concerns a method for removing phenols from their aqueoussolutions by means of molecular sorption with resins having low ionexchange capacity, both of the sulfonated cation exchange type and or"the quaternary ammonium anion exchange type. More particularly, theinvention concerns a method for removing phenols from streams andaqueous industrial wastes by passage through a water-immersed bed of alow-capacity quaternary ammonium anion exchange or a low-capacitysulfonated cation exchange resin.

It has been proposed in the past to remove a dissolved phenol from anaqueous solution by passage through a bed of a strongly basic quaternaryammonium anion exchange resin in its salt form. The dissolved phenol wassorbed by the strongly basic quaternary ammonium anion exchange resinand was thereby removed from its aqueous solution. The solution wasdrained or washed from the resin, after which the sorbed phenol waseluted from the resin by washing the same with a water-miscible organicliquid, e.g., methanol. This method used a conventional quaternaryammonium anion exchange resin in its salt form, e.g., the sulfate,chloride, nitrate or phenate form. Such conventional resins have fromtwo-thirds to one functional quaternary ammonium group per aryl nucleus.

It has now been discovered that low-capacity salt form quaternaryammonium anion exchange resins and lowcapacity acid or salt forms ofsulfonated cation exchange resins having from to 60 percent of theamount of functional groups as are present in conventional sulfonated orquaternary ammonium ion-exchange resins are particularly suitable forremoving phenols from their aqueous solutions. Such low-capacityion-exchange resins sorb phenols more tenaciously than the conventionalquaternary ammonium anion exchange resins previously used.

The anion and cation exchange resins of this invention have from 10 to60 percent as many quaternary ammo nium anion exchanging or sulfonatecation exchanging groups as conventional quaternary ammonium orsulfonate ion-exchange resins. The low-capacity resins used in theprocess of this invention advantageously have their quaternary ammoniumor sulfonate groups uniformly distributed throughout their resinouspolymeric matrixes.

The low-capacity quaternary ammonium anion exchange resins used in theprocess of this invention are made by suspension polymerizing at aboutto C. vinylbenzyl chloride or bromide together with one or more othermonoalkenyl aryl coinonomers and a crosslinking dialkenyl monomer,suitably divinylbenzene, in

proportions from 10 to 60 mole percent vinylbenzyl f halide, 0.1 to 10mole percent dialkenyl monomer, the balance being one or moremonoalkenyl aryl monomers.

d'i fihd Patented Apr. 20, 1965 Thereafter, the resulting particulatepolymeric vinylbenzyl halide is reacted, advantageously at 20 to C.,with a tertiary amine of the type used in making conventional quaternaryammonium resins in amount suiiicient and for a time sutlicient to reactwith the benzylic halide groups to give the corresponding low-capacityuniformly distributed quaternary ammonium halide substituted resins. Thecourse of the quaternization reaction to completion is followed byperiodic capacity tests. The reaction product is advantageously washedwith acetone and water. It is used in the salt form, e.g., sulfate,chloride, nitrate or phenate form.

The low-capacity suifonated cation exchange resins used in the processof this invention are made by swelling a polymeric alkenylaromatic resincross-linked with between 0.1 and 10 mole percent of a diallrenylcross-linking agent, with a swelling agent which is also an inertsolvent for chlorosulfonic acid, admixing chlorosulfonic acid in amountsufficient to monosulfonate from 10 to 60 percent of the available arylnuclei, and gradually heating the mixture of swollen resin andchlorosulfonic acid to a sulfonation temperature of about 20 to 20 C.for a time sufficient uniformly to monosulfonate from 10 to 60 percentof the available aryl nuclei as determined by periodic capacity tests.The reaction product is washed with water. It is used in the acid orsalt form, e-.g., the hydrogen or sodium form.

In making the polymeric l0w-capacity anion and cation exchange resinsused in this invention, conventional dialltenyl cross-linking agents inamount from 0.1 to 10 mole percent of the base or matrix resin polymerare used. They include divinylbenzenes, divinyltoluenes, divinylxylenes,divinyl naphthalenes, divinylethylbenzenes,, di' allyl esters,diacrylate esters, etc. Resinous alkenylaryl polymers which aresubsequently sulfonated to give lowcapacity cation exchange resins areadvantageously those of styrene, vinyltoluenes, vinylxylenes,vinylnaphthalenes, vinylethylbenzenes, alpha-methylstyrene,vinylchlorobenacne, and mixtures thereof. The polymeric vinylbenzylhalides used to make the quaternary ammonium resins utilized herein arethose containing the preceding monomers and mixtures thereof alsocontaining from 10 to 60 mole percent combined vinylbenzyl chloride orbromide.

Phenols which can be removed from their aqueous solutions by thesalt-form of water-wet low-capacity anion and the salt or acid form ofcation exchange resins described above are the monohydric phenols,nuclearly substituted derivatives thereof containing one or more halosubstituents such as chloro or' bromo, or alkyl, aryl, aralkyl,cycloalkyl or alkoxy groups, all of which are directly attached to thearyl nucleus. Examples of phenols which can be sorbed from their aqueoussolutions by the method herein described are phenol, o-, m-, andpcresol, xylenol, chlorophenol, trichlorophenol, brom0- phenol,ophenylphenol, p-tertiary-butylphenol, pentachlorophenol, guaiacol,ethylphenol, nitrophenol and carvacrol. Such phenols can be sorbed fromtheir aqueous solutions containing as little as one ppm. phenol.

In practice, the water-wet low-capacity sul-fonated cation exchangeresin in a salt or acid form or low-capacity quaternary ammonium anionexchange resin in a salt form is contacted with an aqueous solution ofthe phenol to be sorbed. Advantageously, the aqueous phenol solution isa fed to a Water-wet bed of a salt form of the low-capacity quaternaryammonium anion exchange resin, preferably and the data for all theresins are summarized in following Table II.

fined in the claims.

Table I.Srpfi0n of phenol by cation-exchange resin with a capacity of0.56 meq. per g.

Run Number 1 i 2 3 4 5 6 Wei ht 01 Resin .=W 0. 987 0. 989 0 002 0. 0051.51 3. 00 Volgme ofPhenof i' s""t''11 0 0 ooi 0 m 0 ooooi 0 0 00i 0oooooi e a 1 1on=1 e Y 0 1 1 c Ore p 0 0. 0778 0. 00704 0 000704 0.0000004 0 00000758 0. 00000174 gorpuon 1. 34 0.110 0. 012 0.00170 0.00030 0. 000035 sor tion, mmol. per g.=6=\,'//W 1. 30 0.117 0.0121 0.00171 0 000100 0.00001 7 Distribution Coclllcient=D= /M 17.5 15.3 151324.6 26. 6.12

chloride or sulfate or of a salt or acid form of the loW- TableII.Szm1mary of sorption data capacity sulfonated cation exchange resinat a rate such that the phenol solute is substantially completely sorbedResin MEXW 5 D by the resin and is removed from the solution. Theeflluent liquor which is substantially free of phenol is drained 77. 17.L l. i. away from the resin or is flushed therefrom w th water. Dowexm)50 X8 0'56 mcqjgum 0.764 12,1 0% Preferably before phenol breakthrough,the resin 1s wasned 1. 7% 35.2 o D1 a all... with a water-misciblesaturated lower ahphauc alcohol, mm .0117 5 e.g., methanol, to removethe sorbed phenol from the resin. g 1 g Thereafter, the cycle ofoperations is repeated. Two or Dowcx 00-Xs 0.70 med/e 0. 777 10.0 30.5more beds of resin may be operated in parallel so that gggg 3% $8 one ofthe beds is being desorbed While the other bed 1s 03?? 05 1 8 74. g 1 Lbeing used to sorb phenol from its aqueous solution. 102 41.6 Flow ofthe aqueous solution or the water-miscible alcohol 5 DOWGX fill-X8 -lg og g may .be either up-fiovv or down-flow through the resin bed. 00314(1172 2171 I The phenol may be separated from the alcohol solvent 1n 3;?93g 3:; 1 l r' llization. Alter- 0.42 113 13.4 usual ways, e.g., bydistil ation or c ysta+ Dowex X83 01 meg-lg 0818 715.8 19.3 natlvely,aqueous phenol solut1on is contacted Wlth a water- I .0758 24 29. 0 wetlow-capacity ion-exchange resin, as described above, 8, 33 &3? untilequilibrium is reached. The resin is then separated 8 from residualliquor as by filtering and processed as above Dowex 504% 5'2 mecug 7 g:9 to de-sorb the phenol and regenerate the resin for re-use. gg 13g 11.2The following examples describe preferred embodi- 4 100183 m m ments andthe best mode contemplated by the inventor for lfi g 2,2 2 31 1 carryingout the invention. The examples are in illustra- Dowex 1-X81.16 meqJg 0.200 05.7 235 two and not in limitation of the invention, wh1ch 13 de- 82 231 .00091 .0004 100 EXAMPLE 1 2 2-3 i 3 s 4 7 0. 5 Dowex 1-X8 2.30meq./g 0. 43% 54. 1 122 .04 .00 14s A 881163 of 6 quantities oflow-capacity chloride form 00420 0. 510 120 quaternary ammonium anionexchange resins having ca- 23 1 Q 8 3 10S pacities of 2.35 and 1.15rneq/g, and a control, a con- 1 34 0. 20 L300 50.0

s s G ventional Dowex 1-X8 quaternary ammonium anion ex- X8 P 252 changeresin in the chloride form having a capacity of 3.4 o sg 10:: meq/g. and6 quantities of low-capacity acid form 0111- fonated cation exchangeresin with capacities of 3.02, 2.03, 0.76 and 0.50 meg/g. together witha control, a h P r s 1, the sqrptlon per gram conventional Dowex 50-X8sulfonated cation exchange of i 1S Plotted agamst thevconcemmtlon ofP1151101 at resin in the acid form and having a capacity of 5.2 meg/g,fiqlilhbnum on a 3 basis The 1 of the.two all capacities being expressedon the dry resin weight basis, gfigfi i g g gi ig g f gs z ifd i areOmitted and the resins all being 200 to 400 mesh, were weighed b emf 1into flasks Known volumes f stand d he 1 lot 11 Accompanying FEGURE 2pmsems plots of log D 6d dfi O P 2 log molarity of phenol where D is thedistribution covgere i e 1 elertrgoncentra Ion r as efficient, i.e., themillimoles of phenol sorbed per g. of dry t 6 mixtures were 1 rated bystanduig for 20 hours at resin divided by the molarity of phenol. Thedecrease in room temperature with occasional shakmg. Portlons oftsorption at very Small concantmfions and differences the solutions werethen suitably diluted, and the phenol among the various resins arerevealed more clearly here contents of the diluted solutions weredetermined by the than in FIGURE 1. colorimetric method described atAnal. Chem. 23:1733 (1951), using a Beckman DU spectrophotometer at 510EXAMPLE 2 An aqueous ppm. 2,4,5-trichlorophenol solution h detailed datafor the catlon E g W a containing 32 weight percent hydrogen chloridewas fed pacity of 0.56 meq. per g. are glven 1n rollowmg Table I 7 to abed of a 2 percent divinylbenzene cross-linked sulfonated polystyrenecation exchange resin in the acid form having a water content of 48.2Weight percent and a dry Weight capacity of 1.5 meq./ g.

After 40 bed volumes of efiluent had been collected, the trichlorophenolconcentration in the efiiuent was still less than 2 ppm. After 80 bedvolumes of effluent had been collected, the trichlorophenolconcentration therein had risen to 16 ppm. Thereafter the resin bed wasregenerated.

The procedure of Example 2 when repeated with a lowcapacity quaternaryammonium anion exchange resin in the chloride form having a capacity of1.16 meq./g., dry basis, gives better sorption than can be obtained withthe salt or acid form of low-capacity sulfonated cation exchange resins.This is in agreement with the observations that low-capacity quaternaryammonium anion exchange resins in the salt form, within the rangeclaimed, have superior sorption as compared with low-capacity sulfonatedcation exchange resins, within the range claimed.

The sorption of phenols with low-capacity resins of this invention doesnot follow the Freundlich equation.

What is claimed is:

1. A method for removing a phenol from an aqueous solution thereof bycontacting said aqueous solution with a low-capacity member of the groupof salt form quaternary ammonium anion exchange resins and salt and acidform sulfonated cation exchange resins, said resins having from 10 to 60percent of their available nuclei substituted by a functionalion-exchanging group of the class consisting of quaternary ammonium saltand sulfonate groups, respectively, whereby the phenol is sorbed by theresin and is removed from the solution.

2. The method of claim 1 wherein the phenol is phenol.

3. The method of claim 1 wherein the phenol is 2,4,5- trichlorophenol.

4. The method of claim 1 wherein the low-capacity ion exchange resin isa quaternary ammonium anion exchange resin having from 10 to 60 percentof its available nuclei substituted by a quaternary ammonium salt group.

References Cited by the Examiner UNITED STATES PATENTS 2,254,745 9/41Jannek 2 60-627 X 2,343,165 2/ 44 Adler 2.60-627 2,861,948 11/58McKcllar 260-621 X 2,911,363 11/59 Kissling 260-621 X 2,937,142 5/60Rios 260-627 X OTHER REFERENCES Bafna et a1.: Ind. and Eng. Chem,48:310-17 (1956), 8 pages.

LEON ZITVER, Primary Examiner. CHARLES B. PARKER, Examiner.

1. A METHOD FOR REMOVING A PHENOL FROM AN AQUEOUS SOLUTION THEREOF BYCONTACTING SAID AQUEOUS SOLUTION WITH A LOW-CAPACITY MEMBER OF THE GROUPOF SALT FROM QUATERNARY AMMONIUM ANION EXCHANGE RESINS AND SALT AND ACIDFORM SULFONATED CATION EXCHANGE RESINS, SAID RESINS HAVING FROM 10 TO 60PERCENT OF THEIR AVAILABLE NUCLEI SUBSTITUTED BY A FUNCTIONALION-EXCHANGING GROUP OF THE CLASS CONSISTING OF QUARTERNARY AMMONIUMSALT AND SULFONATE